Multiply 1-digit numbers by decimals | Maths | Quizalize & Oak National Academy

Starter quiz

Count up in 25s. What would come next? 25, 50, ______

'75' ✓
Match the factors to their product.

3 × 10 =

⇔

30 ✓

14 × 10 =

⇔

140 ✓

103 × 10 =

⇔

1030 ✓

2.1 × 10 =

⇔

21 ✓

0.5 × 10 =

⇔

5 ✓
Match the expressions to their answer.

40 × 0.1

⇔

4 ✓

150 × 0.1

⇔

15 ✓

15 × 0.1

⇔

1.5 ✓

4 × 0.1

⇔

0.4 ✓

0.4 × 0.1

⇔

0.04 ✓
Match the equivalent expressions.

53 × 0.1

⇔

53 ÷ 10 ✓

5 × 0.01

⇔

53 ÷ 100 ✓

53 × 1

⇔

53 ÷ 1 ✓

5.3 × 0.1

⇔

5.3 ÷ 10 ✓

5.3 × 0.01

⇔

5.3 ÷ 100 ✓
Lucas has 1.8 kg flour. Sofia has one-tenth times this amount. How much flour does Sofia have? ______ kg

'0.18' ✓
Sofia’s flower is 87 cm tall. Lucas’ has only grown to one-hundredth times this height. How tall is Lucas’ flower? ______ cm

'0.87' ✓

Exit quiz

If 9 × 14 = 126, what does 9 × 1.4 equal?

126

12.6 ✓

1.26

0.126
Calculate 9 × 2.5 = ______

'22.5' ✓
Use unitising and known facts to match the equation to its product.

0.04 × 8 =

⇔

0.32 ✓

0.07 × 6 =

⇔

0.42 ✓

0.9 × 5 =

⇔

4.5 ✓

4 × 0.3 =

⇔

1.2 ✓

3 × 0.8 =

⇔

2.4 ✓
Calculate this: 3 × 8.7 = ______

'26.1' ✓
Plums cost £2.35 per kilogram. Sofia buys 4 kilograms of strawberries. How much does she spend? £______

'9.40' ✓
Sofia buys eight stickers. They cost £0.52 each. How much do they cost altogether? £______

'4.16' ✓

Worksheet

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Lesson Details

Key learning points

Use place value to convert the decimal fraction by multiplication to a whole number.
Use unitising, known facts and/or the distributive law to multiply the whole numbers.
Use place value to convert the number by division to adjust the product.

Common misconception

Children may scale the decimal fraction inaccurately or may forget to scale the product accordingly to solve the original equation.

If a decimal fraction has only tenths, we multiply by 10 to form a whole number. If the decimal fraction has hundredths, we multiply by 100 to form a whole number. Remember to adjust the product to answer the original equation.

Keywords

Unitising - Treating groups that contain the same number of things as ‘ones’ or ‘units’. It is important particularly in handling money and in understanding place value and supports us to think multiplicatively.
Distributive law - The distributive law says that multiplying a number by a group of numbers added together is the same as doing each multiplication separately.